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Hormone refractory Prostate Cancers more
likely to spread to other organs
Newswise — Prostate cancers that are resistant to androgen
deprivation therapy are more invasive and
more likely to spread to other organs than
androgen dependent prostate cancers, UCLA
cancer researchers have found.
Virtually all prostate cancers are androgen dependent at first, but
they progress and become resistant over
time. These hormone refractory or castration
resistant cancers can grow despite surgical
or medical therapies that deplete
testosterone.
The UCLA study is the first to link that progression with the
cancer’s tendency to spread to other organs.
The findings could change the way some prostate cancers are
treated, spurring earlier use of hormone
therapy to prevent the cancer’s spread, said
Dr. Robert Reiter, a professor of urology, a
researcher at UCLA’s Jonsson Cancer Center
and senior author of the study.
Published in the Feb. 15 issue of the journal Cancer Research, the
study makes the connection between androgen
receptor and the spread of prostate cancer
as well as the progression to androgen
independence.
Previous studies have shown that the androgen receptor is
responsible for the growth of hormone
refractory prostate cancer. However, no one
has associated the spread of prostate cancer
to the androgen receptor, Reiter said.
“We started noticing that the castration resistant prostate cancer
models in the lab seemed to express genes
that are typically associated with the
spread of cancer,” Reiter said.
“We began to ask what cell signaling pathways might be responsible.
We looked at the androgen receptor and were
surprised to find that it was not only
overexpressed in castration resistant
cancers but also in invasive cancers that
still relied on androgen to grow.”
The study found that overexpression of the androgen receptor was
critical to the cancer becoming more
invasive. If a therapy could be found that
blocked overexpression of the receptor, it
might prevent the spread of certain prostate
cancers.
Traditionally, doctors don’t like to use hormone treatment – which
stops the production of testosterone - early
on in the treatment of prostate cancer
because of the harsh side effects, which can
include hot flashes, osteoporosis and sexual
dysfunction.
In the past, doctors have waited until the cancer spread to
prescribe hormone therapy, Reiter said.
“This study may provide additional scientific rationale to support
the recent trend that giving hormone
treatment early on is better than waiting,”
Reiter said.
“Early hormone treatment in this group of men might allow them to
live longer. High levels of androgen
receptor in the primary tumor might also
predict which cancers are more likely to
spread despite initial surgery or
radiation.”
This strategy could be particularly effective in high risk men,
those with large primary tumors, high
Gleason scores and those that have lymph
node involvement at diagnosis.
Prostate cancer is the most common cancer in men in the United
States. This year alone, more than 218,000
men will be diagnosed with prostate cancer.
About 27,000 men will die from the disease.
Reiter and his team will next seek to understand the mechanism by
which androgen receptor overexpression is
causing the cancer to spread. If they can
uncover the mechanism, they might find new
and better targets for drug therapy in
addition to targeting the androgen receptor.
UCLA's Jonsson Comprehensive Cancer Center comprises about 235
researchers and clinicians engaged in
disease research, prevention, detection,
control, treatment and education.
One of the nation's largest comprehensive cancer centers, the
Jonsson center is dedicated to promoting
research and translating basic science into
leading-edge clinical studies.
In July 2007, the Jonsson Cancer Center was named the best cancer
center in California by U.S. News & World
Report, a ranking it has held for eight
consecutive years. For more information on
the Jonsson Cancer Center, visit our Web
site at
www.cancer.ucla.edu.
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